local voucherId = ARGV[1]
local userId = ARGV[2]
local stockKey = 'seckill:stock:' .. voucherId
local orderKey = 'seckill:order:' .. voucherId

if(tonumber( redis.call('get',stockKey)) <= 0 ) then
    return 1
end
if(redis.call('sismember',orderKey,userId) == 1) then
    return 2
end
redis.call('incrby',stockKey,-1)
redis.call('sadd',orderKey,userId)
return 0